Question: $-5ab + 10b + 7c + 9 = -b + 9c - 3$ Solve for $a$.
Combine constant terms on the right. $-5ab + 10b + 7c + {9} = -b + 9c - {3}$ $-5ab + 10b + 7c = -b + 9c - {12}$ Combine $c$ terms on the right. $-5ab + 10b + {7c} = -b + {9c} - 12$ $-5ab + 10b = -b + {2c} - 12$ Combine $b$ terms on the right. $-5ab + {10b} = -{b} + 2c - 12$ $-5ab = -{11b} + 2c - 12$ Isolate $a$ $-{5}a{b} = -11b + 2c - 12$ $a = \dfrac{ -11b + 2c - 12 }{ -{5b} }$ Swap the signs so the denominator isn't negative. $a = \dfrac{ {11}b - {2}c + {12} }{ {5b} }$